STP32

Introduction

A year or two ago the subject of standardizing corrosion testing was brought up for discussion independently in our ferrous and non-ferrous groups. It was decided to appoint a joint committee to obtain papers on various kinds of corrosion testing. We trust that the facts brought out will form a sound basis for further study of the subject by this Society. There is now substantial agreement on the mechanism of corrosion and the influence of various factors, and much is known of the therapeutics of this “disease” of metals, so that we may approach with some confidence the subject of standardization of corrosion testing procedure. Many tests for the physical properties of metals in environments that do not seriously attack the metal have been standardized, but comparatively little has been done towards the establishment of standard tests of the influence of surrounding conditions on various metals. The latter problem is complicated by factors associated both with the metal and its environment, which factors as a rule bear no relation whatever to the physical properties of the metals, but often involve complex surface chemistry phenomena. Unless controlled, corrosion may seriously reduce the useful life of metals either by changes in their structure or section. To start with then, it is important to recognize the fact that the metals most used in construction and others that are less commonly used are essentially unstable forms of matter having more or less tendency to revert to their more stable compounds with release of free energy. It is now generally recognized that when corrosion has started on any specific metal, factors associated with the environment have, as a rule, much more to do with the deterioration of the metal than its composition.